An Efficient Optoelectronic System for Remote Salinity Water Sensing

Abstract

In this work, we proposed and demonstrated an efficient optoelectronic system capable to detect 1 gram of salt per liter of water (0.1% salinity) in real time employing optical fiber technology as sensing medium and embedded systems of National Instruments Company to get an accurate instrumentation process. In addition, the sensitivity of this salinity sensor can be enhanced by reducing the diameter of the optical fiber sensor structure ( by employing a controlled tapering process. More specifically, the sensitivity of this device has been raised from 141.933 nm/Refractive Index Unit (RIU) for an un-tapered sensor structure to 352.915 nm/RIU for a tapered sensor structure . In fact, considering that the tapered sensor structure provides an approximately linear response with a maximum sensitivity of 0.6624 nm / % salt, the percentage of salt is easily identified by monitoring the peak wavelength response.

Sensitivity enhancement experimental demonstration using a low cutoff wavelength SMS modified structure coated with a pH sensitive film

“…In this paper, we present a less expensive pH sensor with higher sensitivity by unit compared to the previously cited researches. Particularly, the optical fiber pH sensors can be applied in: biochemistry [14,15], structural monitoring [16] and energy [17,18,19].…”